The present invention relates to an apparatus for dispensing viscous compounds, especially dental materials.
The apparatus comprises a dispensing device to which a sleeve is detachably attached whereby the dispensing device has a rotary drive with which via a plunger pressure is applied to the compound received in a container for dispensing the compound through the sleeve.
Such an apparatus is known from German Patent 27 41 185. In this device a rotary drive is provided which is embodied as a nut that is rotatably supported on a housing.
The threaded rod has a trapezoidal thread with great pitch, and a preadjustment of the apparatus is possible by a manipulator acting on the threaded rod.
The apparatus is used such that the manipulator at the end of the threaded rod is held between thumb and index finger and the nut is then turned by the thumb. This allows for a fine adjustment.
The dispensing or pressing out of viscous compounds from sleeves, which may be part of a capsule or cartridge, requires, depending on the respective situation, greatly different actuation forces. When rather liquid, but still viscous compounds must be dispensed from sleeves with a small diameter, the actuating forces are minimal. However, when relatively viscous materials must be pressed out of cartridges with large diameter, especially when through a narrow tip, rather great actuating forces are required. The aforementioned patent suggests an alternative embodiment of the apparatus made of metal. However, this apparatus, because of its size and because of the relatively great pitch, is suitable substantially only for compounds in thin sleeves.
In order to accommodate various types of applications, it has been customary to employ complete syringes as disposable articles. They comprise a rotary drive which is adjusted in its size to the compound to be dispensed. This allows for a relatively precise adaptation according to the specific requirements. However, it is disadvantageous that considerable amounts of plastic waste are produced which possibly is even greater than the amount of the dental material to be dispensed.
In numerous other designs, pistol-shaped apparatus are known in which a sleeve filled with dental material is used and the actuation of the pistol grip causes dispensing of the dental material from the sleeve. It is possible to realize dispensing forces that surpass up to five times the manually applied force by employing respective gear ratios in order to be able to dispense compounds of high viscosity.
On the other hand, a rotary drive is easier to fine adjust and is basically also suitable for transmitting large actuating forces.
It is therefore an object of the present invention to provide an apparatus of the aforementioned kind which is suitable for dispensing compounds from sleeves having a relatively large diameter whereby the compounds are highly viscous and whereby a fast adaption to the filling degree of the sleeve is possible. Furthermore, no separate disposable dispensing device for each sleeve should be required.